Bespoke deployment line extension

ABSTRACT

A downhole tool deployment system including a tool string for insertion into a well, a deployment line configured for attachment to the tool string to lower the tools string into the well, and a line extension configured for attachment to the deployment line and the tool string for insertion between the deployment line and the tool string, the line extension having properties different from or similar to the deployment line.

FIELD OF THE INVENTION

This invention relates generally to mechanical devices used in wellssuch as oil and gas wells. More particularly, apparatuses and methodsare provided for enabling the deployment of downhole tools in wells withintervals presenting special or hazardous conditions outside theoperation envelop of existing deployment lines. A deployment line may bea slickline, braided line, electromechanical line, or a flexible rod.

DESCRIPTION OF THE RELATED ART

A variety of downhole mechanical devices or tools are used in wells, forsuch purposes as logging the properties of the fluids in the well orformations surrounding the well, taking samples of the formation rocksor fluids, perforating the formations and/or wellbore casing, performingwell interventions, and other purposes.

The deployment line types typically used are referred to as slicklines,braided lines, electromechanical lines, or flexible rods. The mostpopular deployment lines are electromechanical lines made up of a centerpackage with one or more electrical conductors encapsulated by twolayers of armoring steel wires. These lines are commonly referred as“wireline cables.”

Slicklines were originally introduced as a metal solid wire used todeploy and retrieve mechanical downhole tools designed to performmechanical services such as installing or removing downhole equipment.In recent years, variations of slickline with electrical and datatransmission capabilities have been introduced. The first variation hasan electrical insulation material laid over the wire to allow datatransmission to the surface acquisition system from downhole toolsoperated from batteries. A second variation is a small diameter hollowtube housing one or more electrical conductors that are used to providethe electrical power and data transmission capabilities required bydownhole tools.

Braided lines are cables typically made up of two layers of solid wiressurrounding a center solid wire. These lines are thicker and strongerthan slicklines and are designed for heavy duty operations not possiblewith slicklines.

Electromechanical lines typically come in two distinctive variations,including those with their external load bearing armor made up withmetal armor wires and referred to as “wireline cable” or “e-line,” andthose made of composite non-metallic materials and referred to as“composite wireline cable” or “composite e-line.” Both variations canhouse a center conductor package containing one or more electricalconductors.

Most wireline cables used in oil and gas wells are made with steel armorwires or special corrosion resistant alloy wires and are used in wellswhere the presence of corrosive mixes such as those containing H2Sand/or CO2 are expected.

Most wireline cables are designed to operate in wells with downholetemperatures less than about 400 F degrees. For wells with higherdownhole temperatures, such as geothermal wells, a variety of“geothermal wireline cables” that include electrical conductors madewith high-temperature insulation materials are required.

Composite wireline cables have higher breaking strength tensions, arelighter, and are more buoyant that their steel wireline cableequivalents, and they can operate in corrosive mix environments.

Flexible rods are made with composite materials. They can house aconductor package with one or more conductors, and they can be used topush tools in highly inclined or horizontal wells.

During the planning stage of well logging or intervention operations,the selection of the deployment line type and length is done consideringa variety of factors, including but not limited to the well boreholegeometry profile, length, and trajectory, the borehole temperature andpressure profiles, the well and formation pressures and fluidproperties, the tensions expected along the length of the wirelinethroughout the job, the speed at which the tool string will need to movethrough the different well intervals, the expected time the wirelinecable will be exposed to hazardous conditions, the type of operationsplanned, and the electrical requirements of the tools to be deployed.Analysis of these factors might reveal the presence of well intervalswith conditions that are unfavorable to the line types commonlyavailable, and the specialty lines and their auxiliary rig up equipmentrequired might not be available in the geographical area of operations.Alternatively, even if the lines are available, they might not be longenough for the target job, or they might be too expensive to buy orrent. Under these circumstances well operators end up using alternativedeployment methods that take more time, are more expensive, and/orrender outcomes of less quality and completion than those achievablewith deployment lines. Examples of alternative deployment methods tooperations planned with wireline cables include usingLogging-While-Drilling tools deployed with drill pipe during the welldrilling stage and using battery-powered logging and intervention toolsdeployed with tubing.

Examples of hazardous conditions present in cased and open holeintervals of oil and gas wells include borehole temperatures higher than400 degrees F. that can tend to soften the electrical conductorinsulating jackets and result in catastrophic short circuits, andcorrosive fluid mixes with high enough concentrations of H2S and/or CO2at high-enough hydrostatic pressure to compromise the integrity of thewireline cable's steel armor wires to the point that the cable can breakapart. Geothermal wireline cables are effective means of deploying toolstrings in hot wells. They are, however, hard to find, expensive, andnot available in most oil and gas markets. Wireline cables made withwires of corrosion resistance alloys are popular in markets with knownfields producing H2S and/or CO2 in high concentrations. They are,however, several times more expensive and have lower working tensionlimits than their steel wire equivalents.

Some well operations in cased well intervals, such as those usingballistic perforating guns, are expected to result in large dynamicloads applied to the wireline cable-tool string anchoring systems. Insuch operations, using a deployment line of insufficient strength canresult in breaking the anchoring point and dropping the tool string intothe well. Changing a wireline cable for a thicker stronger one might notbe possible if not readily available with the required length because itmay require different cable anchoring, rig-up, and pressure controlequipment parts, and it may still not survive the job dynamic loads.

Logging or fluid/formation sampling operations performed in open holeintervals that include formations with fluid pressures significantlylower than the hydrostatic pressure in the borehole are effectivedifferential pressure traps where the tool string and the deploymentline can become hydraulically attached to the borehole wall. Theseunwanted conditions are referred to as differentially sticking. Failureto free the stuck deployment line and/or the stuck tool string typicallyrequires the execution of a long and expensive fishing operation usingdrill pipe. Tool strings can include anti-sticking devices such asroller stand-off subs and jar tools to allow using hard pulls on thedeployment line to free the stuck tool string. To prevent wirelinecables becoming differentially stuck over a selection of open holeintervals, wireline stand-off subs may be mounted over selected sectionsof the wireline cable. These wireline stand-off subs also prevent thewireline cable from cutting a groove in soft rocks—a condition referredto as cable key-sitting. If this happens over a permeable formation, thewireline cable will eventually become differentially stuck.

The accessibility to wireline cable stand-off subs is extremely limited.A detailed pre-job analysis is required to determine the open holeintervals where the wireline cable is likely to get key-seated ordifferentially stuck while performing stationary formation or fluidsampling operations that often take several hours to complete, acondition that makes differentially sticking significantly more likely.Since not all the key information required by the pre-job analysis isknown in exploration wells, it may not be possible to know over whichsections of the wireline cable the wireline stand-offs should bemounted. The stand-offs are mounted on the wireline cable over theselected intervals while running the tool string in the hole. Stoppingthe downhole tool string and wireline cable descent to mount onestand-off at a time adds several hours of rig time that drivesadditional cost and increases the hole degradation since no mudcirculation is possible while performing the job. The stand-offs aremounted only over selected sections of the wireline and not over theentire length of the cable deployed within the open hole section of thewell. The length of the wireline expected to travel below the selectedsticky intervals can become key-seated or differentially stuck since itdoes not have stand-offs mounted. This makes the use of wirelinestand-offs for non-stationary “moving” wireline operations ineffective,which results on these operations being done using alternative expensiveand time-consuming drill pipe deployment methods, such asLogging-While-Drilling or Pipe-Conveyed Logging.

BRIEF SUMMARY OF THE INVENTION

The inventions subject of this document address the shortcomings of thecurrent art listed in the previous section and enable new applicationsand services by introducing methods and apparatuses to interconnect twoor more lengths of the same or different deployment line types, add lineextension(s) designed to operate under the anticipated special orhazardous conditions, and insert downhole tools between line lengthsusing field line and tool connections.

While the embodiments and methods that follow are directed toapplications comprising a “wireline cable” having one or moreconductors, it should be understood that each embodiment mayalternatively comprise other forms of lines allowing the deployment oftool strings, including, but not limited to, slicklines, braided lines,electromechanical lines, flexible rods, or similar means of conveyance.

One aspect of the present technology provides a downhole tool deploymentsystem that includes a tool string for insertion into a well, adeployment line configured for attachment to the tool string to lowerthe tools string into the well, and a line extension configured forattachment to the deployment line and the tool string for insertionbetween the deployment line and the tool string, the line extensionhaving properties similar to or different from the deployment line.Certain embodiments may also include an interconnecting tool forinsertion between the line extension and the deployment line.

In some embodiments, the interconnecting tool can be an adapterconfigured to connect the line extension and the deployment line if theline extension and the deployment line are not directly connectable.Furthermore, the interconnecting tool can be at least one logging toolor at least one well intervention tool. In some embodiments, thedownhole tool deployment system can further include at least onestandoff mounted on the line extension. The at least one standoff can bea short prolate ellipsoid shape. In certain embodiments, the lineextension can be designed to operate in high-temperature environments upto 600 F, and/or it can be made using corrosion resistant alloy steelsuitable for moderate H2S and CO2 environments and/or electricalconductors made of nickel-plated wires adhering to ASTMBB355 Class 10for increase corrosion resistance.

Another aspect of the present technology provides a method of deployinga tool string into a well. The method includes the steps of attaching adeployment line to a line extension, the line extension having similaror different properties than the deployment line, attaching the lineextension to the tool string, and inserting the tool string into a wellusing the deployment line and the line extension. This method can alsoinclude attaching at least one stand-off to the line extension.

In some embodiments, the tool string, line extension, and deploymentline can be connected with tool connections. In addition, the method canfurther include the step of inserting an interconnecting tool betweenthe line extension and the deployment line. The interconnecting tool canbe an adapter configured to connect the line extension and thedeployment line if the line extension and the deployment line are notdirectly connectable. The interconnecting tool can be at least onelogging or at least one intervention tool.

Yet another aspect of the present technology provides a method oflogging a well with problematic intervals. The method includes the stepsof lowering a deployment line, a line extension, and a tool string intoa well, the line extension having different properties than thedeployment line, the properties of the line extension configured toallow the line extension to resist conditions in the problematicintervals. The method further includes the steps of passing only thetool string and the line extension into the problematic intervals of thewell and performing logging operations at desired locations in the well.

In some embodiments, the problematic intervals can be of a hightemperature and/or corrosive. Alternatively, the problematic intervalscan have a high-pressure differential. In addition, the deployment linecan remain above the problematic intervals in the well during loggingoperations.

BRIEF DESCRIPTION OF THE DRAWINGS

The present technology will be better understood on reading thefollowing detailed description of non-limiting embodiments thereof, andon examining the accompanying drawings, in which:

FIG. 1 is a representative system overview of the major componentsrequired to deploy a tool string in a well using a deployment line.

FIG. 2A shows a single strand (slick line) wire that can be used toservice oil and gas wells.

FIG. 2B shows a braided line that can be used to service oil and gaswells.

FIG. 2C shows a single-conductor wireline cable that can be used toservice oil and gas wells.

FIG. 2D shows a seven-conductor wireline cable that can be used toservice oil and gas wells.

FIG. 2E shows an alternate single-conductor wireline cable that can beused to service oil and gas wells.

FIG. 2F shows another single-conductor wireline cable that can be usedto service oil and gas wells.

FIG. 2G shows a smooth two-conductor wireline that can be used toservice oil and gas wells.

FIG. 2H shows a flexible rod with a 2-conductor coaxial package that canbe used to service oil and gas wells.

FIG. 3A is a schematic diagram showing the rigging setup to connect adeployment line to a tool string.

FIG. 3B shows a schematic diagram of the deployment line and tooldeployed in a well.

FIG. 4A is a schematic diagram showing the rigging setup for adeployment system according to an embodiment of the present technology.

FIG. 4B is a schematic diagram of the deployment system deployed in awell according to an embodiment of the present technology.

FIG. 5A is a schematic diagram of a tool and line extension connectionaccording to an embodiment of the present technology.

FIG. 5B is a schematic diagram of an interconnection tool and lineextension connection according to an embodiment of the presenttechnology.

FIG. 5C is a schematic diagram of a deployment line and interconnectiontool connection according to an embodiment of the present technology.

FIG. 5D is a schematic diagram of deployment system that is ready to bedeployed to a well according to an embodiment of the present technology.

FIG. 5E is a schematic diagram of a deployment system according to anembodiment of the present technology that is deployed into a well.

FIG. 6A is a schematic diagram of a tool and line extension connectionaccording to an embodiment of the present technology.

FIG. 6B is a schematic diagram of a deployment line and line extensionconnection according to an embodiment of the present technology.

FIG. 6C is a schematic diagram of a deployment system according to anembodiment of the present technology that is deployed into a well.

FIG. 6D is a schematic diagram of a deployment system deployed intoproblematic intervals within a well according to an embodiment of thepresent technology.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing aspects, features and advantages of the present technologywill be further appreciated when considered with reference to thefollowing description of preferred embodiments and accompanyingdrawings, wherein like reference numerals represent like elements. Indescribing the preferred embodiments of the technology illustrated inthe appended drawings, specific terminology will be used for the sake ofclarity. The invention, however, is not intended to be limited to thespecific terms used, and it is to be understood that each specific termincludes equivalents that operate in a similar manner to accomplish asimilar purpose.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements. Anyexamples of operating parameters and/or environmental conditions are notexclusive of other parameters/conditions of the disclosed embodiments.Additionally, it should be understood that references to “oneembodiment”, “an embodiment”, “certain embodiments,” or “otherembodiments” of the present invention are not intended to be interpretedas excluding the existence of additional embodiments that alsoincorporate the recited features. Furthermore, reference to terms suchas “above,” “below,” “upper”, “lower”, “side”, “front,” “back,” or otherterms regarding orientation are made with reference to the illustratedembodiments and are not intended to be limiting or exclude otherorientations.

The generic deployment configuration included in FIG. 1 illustrates howa wireline cable, or deployment line 102, originally stored in a cabledrum part of a deployment unit 104, can be rigged up using sheave wheels106. In the example shown, one sheave wheel 106 is attached to the drillfloor and the other sheave wheel 106 is attached to the traveling blocksof the deployment rig 108. Also shown is how a tool string 110 canalready be lowered into a well 112 while attached to the deployment line102 to a depth within the open hole section 114 of the well 112. In thisdeployment configuration, the cable length adjacent the tool string 110may be exposed to higher temperatures, higher pressures, corrosivefluids, and different types of rock surfaces than the cable length thatremains within the shallow cased hole section of the well during theexecution of the operation. In addition, the cable length at the surfacegoing through the sheave wheels can support higher tensions that thecable length closer to the tool string 110 during the deployment andextraction phases of the operation.

The cross sections and images included in FIG. 2 depict geometries anddistributions of the load bearing and electrical conductor elements of avariety of deployment lines. For example, FIG. 2 a shows a single strandwire (slick line) covered with an electrical insulating jacket. Thisconfiguration is referred to as a slick-e-line. FIG. 2 b depicts abraided line made of 19 solid steel strand wires of the same diameterwrapped in a 1, 6 and 12 wire layers configuration. FIG. 2 c shows asingle-conductor wireline cable made with two layers of 12 and 18 solidsteel strand wires of the same diameter wrapped over a single electricalconductor made of 21 copper strands and a plastic insulation jacket.FIG. 2 d shows a seven-conductor wireline cable made with two layers of15 and 24 solid steel strand wires of different diameters wrapped over ahard-plastic enclosure containing seven electrical conductors, each madeof 7 copper strands and a plastic insulation jacket. FIG. 2 e shows asingle-conductor wireline cable made with two layers of 12 and 18 solidstrand wires of the same diameter made of a corrosion resistant alloy.These wires are wrapped over a single electrical conductor made of 21copper strands and a plastic insulation jacket. FIG. 2 f shows asingle-conductor wireline cable made with two layers of 12 and 18 solidsteel strand wires of the same diameter wrapped over a single electricalconductor made of 21 copper strands and a high-temperature plasticinsulation jacket. FIG. 2 g shows a smooth two-conductor wireline cablefully embedded within a polymer enclosure that includes an outer layerof 13 3-strand wires, an inner layer of 21 solid strand wires, and a2-conductor coaxial package where the center conductor is made of 7copper strands and the outer conductor is a circular screen made ofmultiple copper threads. The outer conductor, inner and outer steelstrand wires are kept electrically isolated by the enclosure polymermaterial. FIG. 2 h shows a flexible rod including a 2-conductor coaxialpackage where the center conductor is made of 7 copper strands and theouter conductor is a circular screen made of multiple copper threads.

Referring now to FIG. 3 a , there are shown components used to deploytool string 110 into well 112 using a wireline cable (deployment line102). Tool string 110 can typically include several tools which havecompatible tool connections at both ends that allow them to attach toeach other. Connection 300 can be a part of the top tool in the toolstring 110. Connection 300 can be any appropriate means to connectbetween components such as a tool connection or a torpedo splice. Thecable head 302, attached to the deployment line 110, can include acompatible connection 300.

FIG. 3 b shows tool string 110 deployed to the bottom of well 112attached to the deployment line 102. The following sequence of tasks canrepresent how tool strings 110 are currently rigged up and lowered intowells. The first step can be to lift and lower the tool string 110 intothe well 112 using a rig hoist line (not shown). A rig up plate 304 canthen be positioned below the connection 300 at the top of the toolstring 110 such that the rig up plate 304 with tool string 110 can beattached over the rig floor 306. Additional tool string sections can bevertically added using the rig hoist line to lift the next tool sectionover the connection 300 of the previous tool string section andconnecting the tools together. After removing the rig up plate 304, thenow longer tool string 110 can be lowered to the desired depth. The rigup plate 304 can be repositioned at the connection 300 of the uppertool. This process can be repeated for each additional tool.

The next step is to rig up the deployment line 102 using the rigtraveling blocks and sheave wheels 106 (shown in FIG. 1 ). The cablehead 302 can be lowered on top of the connection 300 to securely engagethe connection 300. The rig up plate 304 can be removed after liftingthe tool string 110 sufficiently clear of the rig up plate 304 bypulling the deployment line 102 using the cable drum-winch system partof the deployment unit 104 (shown in FIG. 1 ). The tool string 110 canthen be lowered to the well interval where the planned operation is tobe performed, and subsequently retrieved using the deployment unit 104.Once the tool string 110 is at the surface, the rig up plate 304 can beused to hang the tool string 110 on the rig floor 306. The wirelinecable head 302 can then be disconnected from the connection 300 so thedeployment line 102, cable head 302, and sheave wheels 106 can be riggeddown. To rig down the tool string 110, a rig hoist line can be used tolift the tool string sufficiently clear so the rig up plate 304 can beremoved and the tool string 110 can be hoisted out of the well 112.

As shown in FIG. 3B, the arrangement can result in exposure of thedeployment line 102 to the environment of the open hole 114. Hightemperatures and/or corrosive environments in the open hole 114 maydegrade the deployment line 102 in this arrangement. Without stand-offs,the deployment line 102 may also become differentially trapped againstthe wall of the open hole. Using full deployment lines 102 suitable forthese conditions can be expensive, difficult to procure, and mayintroduce other complications due to lower working tension limits inthese specialized deployment lines 102.

The following descriptions are based on tool string deployments plannedwith a wireline cable, however equivalent descriptions can be made foroperations planned with other types of deployment lines such as slicklines, braided lines, electromechanical lines, and flexible rods.

FIG. 4 a shows one embodiment of the deployment systems according to thepresent technology, including the components used to deploy tool stringsinto wells shown in FIGS. 3 a and 3 b and described above. FIG. 4 ashows additional components including a line extension 400,schematically depicted with spherical shapes added along its length, andan interconnecting tool 402.

The line extension 400 can include a set of specific operationalproperties not provided by the existing deployment line 102, a cablehead 404, and a top connection 406. The line extension 400 can bedesigned with temperature and corrosion resisting properties not presentin the deployment line 102. The line extension 400 may be designed toresist temperatures up to 600 F. For corrosion resistance, the lineextension 400 may be made using corrosion resistant alloy steel suitablefor moderate H2S and CO2 environments and/or electrical conductors madeof nickel-plated wires adhering to ASTMBB355 Class 10 for increasecorrosion resistance. This can provide appropriate protection of thedeployment line 102 suitable for downhole environments without requiringthat the entire cable is made of the same design. The extension cablehead 404 can be any appropriate connection configured for attachment tothe connection 300. The top connection 406 can be any appropriateconnection for attachment to the cable head 302 or interconnecting tool402.

The line extension 400 can also be a sacrificial cable. In thisconfiguration, the line extension 400 can be designed with similar ordifferent temperature and corrosion resisting properties present in thedeployment line 102. After deployment, the line extension 400 can bedisposed of depending on the amount of wear accrued from usage. In thisembodiment, only a portion of the cable, the line extension 400, wouldneed to be inspected and potentially disposed of instead of the entiredeployment line 102.

The interconnecting tool 402 is an optional component that can functionas an adapter between the top connection 406 of the line extension 400and the cable head 302 if need be. The interconnecting tool 402 can alsobe a separate logging or well intervention tool that operates on its ownor that requires the use of one or more conductors of the deploymentline 102.

FIG. 4 b shows the tool string 110 at the bottom of the well 112 afterbeing deployed using the line extension 400, interconnecting tool 402and deployment line 102. In this drawing the length of the extensionline 400 can be sufficient to cover the complete open hole section 114or the well 112 when the tool string 110 is at the deepest possibleposition, while the interconnecting tool 402 can be at the bottom of thecased hole section 408. This configuration can be used when theextension line 400 offers specific operational benefits in the open holesection 114, such as preventing the deployment line 102 from becomingdifferentially stuck, or when the purpose of the interconnecting tool402 is to acquire logging data over the cased hole 408 section of thewell 112.

FIGS. 5 a through 5 e show one embodiment of how to deploy the toolstring 110 to the bottom of the well 112 using an extension line 400 andinterconnecting tool 402. FIG. 5 a shows the tool string 110 hangingfrom the rig up plate 304 and the extension line 400 lifted above therig floor 304 with extension cable head 404 ready to be connected to thetool string top connection 300. FIG. 5 b shows the tool string 110 andextension line 400 hanging from the rig up plate 304 and theinterconnecting tool 402 lifted above the rig floor 306 with its bottomconnection 500 ready to be connected to the extension line topconnection 406. FIG. 5 c shows the tool string 110, the extension line400, and the interconnecting tool 402 hanging from the rig up plate 304and the deployment line 102 lifted above the rig floor 306 with itscable head 302 ready to be connected to the interconnecting tool topconnection 502. FIG. 5 d shows all components connected and attached tothe wireline cable 102 with the well mouth cleared before the cablewinch-drum system of the deployment unit 104 is used to lower the toolstring 110 into the well 112. FIG. 5 e shows the tool string 110 at thebottom of the well 112. After the planned operation is completed, thedeployment line 102 is pulled out of the well until the interconnectingtool 402 is at the surface, as shown in FIG. 5 d . The operationalsequence depicted in FIGS. 5 a, 5 b and 5 c can be executed in reverseorder to remove the interconnecting tool 402, the extension line 400 andthe tool string 110 from the well 112.

FIGS. 6 a through 6 d show another embodiment of an extension line 400used to perform a logging operation in a long open hole section thatincludes two separate problematic intervals 600 and 602. Both permeableintervals 600 and 602 can include severe pressure over balance, whichcan present a high risk of the cable and tool string becomingdifferentially stuck.

The extension line 400 can have an external profile that includes shortprolate ellipsoid shaped stand-offs 604 at pre-defined separationintervals. The stand-offs 604 can result in a significantly smaller areaof contact with the borehole wall of the well, which can reduce thepressure differential sticking forces over these intervals. Thestand-off 604 can be external stand-off subs which can be mounted andmechanically locked over the extension line 402 at selected intervals.The stand-offs 604 can be built-in subs manufactured with stand-offgeometries at selective intervals. The stand-offs 604 can be made ofmetal or hard plastic segments. The stand-offs 604 can be molded overthe extension line 402 with plastic, polymers, or other non-metallicmaterial.

FIGS. 6 a and 6 b show one embodiment of the operational sequence to rigup the tool string 110, extension line 400 that has stand-offs 604mounted over its entire length, and deployment line 102 in a well 112that can include an open hole section with problematic intervals 600 and602, known to have high differential pressures that will likely resulton the deployment line becoming differentially stuck. FIG. 6 c depictsthe depth at which the extension line 400 starts going through theproblematic interval 600 while running the tool string 110 into the well112. FIG. 6 d shows the tool string 110 at the bottom of the well withthe extension line 400 deployed through both problematic intervals 600and 602. The minimum length of the extension line 400 required in thisembodiment is the distance from the top of the problematic interval 600and the bottom of the well minus the length of the tool string 110. Thisensures that no length of the deployment line 102 enters the problematicintervals 600, 602 which can result in the deployment line 102 becomingdifferentially stuck.

It is possible to select and use an extension line of this type when noformations pressure data is available, such in new exploration wells. Anextension line 400 with a length greater than the difference between thetotal well depth and the casing depth can ensure that the deploymentline 102 cannot enter the open hole section of the well. This canprevent the deployment line 102 from becoming differentially stuck orexposed to high temperatures and/or corrosive environments when wellconditions are unknown.

Although the technology herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent technology. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present technology as defined by the appended claims.

1. A downhole tool deployment system, the system comprising: a toolstring for insertion into a well; a deployment line configured forattachment to the tool string to lower the tools string into the well; aline extension configured for attachment to the deployment line and thetool string for insertion between the deployment line and the toolstring, the line extension having the same or different properties fromthe deployment line.
 2. The system of claim 1, further comprising: aninterconnecting tool for insertion between the line extension and thedeployment line.
 3. The system of claim 2, wherein the interconnectingtool is an adapter configured to connect the line extension and thedeployment line.
 4. The system of claim 2, wherein the interconnectingtool comprises at least one logging tool.
 5. The system of claim 2,wherein the interconnecting tool comprises at least one wellintervention tool.
 6. The system of claim 1, further comprising: atleast one standoff built-in or mounted on the line extension.
 7. Thesystem of claim 1, wherein the line extension is designed to operate inhigh-temperature environments up to 600 F.
 8. The system of claim 1,wherein the line extension is made using corrosion resistant alloy. 9.The system of claim 1, wherein the line extension comprises at least oneelectrical conductor made of nickel-plated wires.
 10. A method ofdeploying a tool string into a well, the method comprising: attaching adeployment line to a line extension at a rig floor, the line extensionhaving the same or different properties than the deployment line;attaching the line extension to the tool string at the rig floor; andinserting the tool string into a well using the deployment line and theline extension.
 11. The method of claim 10, wherein the tool string,line extension, and deployment line are connected with tool connections.12. The method of claim 10 further comprising: attaching at least onestand-off to the line extension.
 13. The method of claim 10, furthercomprising: inserting an interconnecting tool between the line extensionand the deployment line.
 14. The method of claim 13, wherein theinterconnecting tool is an adapter configured to connect the lineextension and the deployment line.
 15. The method of claim 13, whereinthe interconnecting tool comprises at least one logging or interventiontool.
 16. A method of logging a well with problematic intervals, themethod comprising: lowering a deployment line, a line extension, and atool string into a well, the line extension having different propertiesthan the deployment line, the properties of the line extensionconfigured to allow the line extension to resist conditions in theproblematic intervals; passing only the tool string and the lineextension into the problematic intervals of the well; and performinglogging operations at desired locations in the well.
 17. The method ofclaim 16, wherein the problematic intervals are high temperature. 18.The method of claim 16, wherein the problematic intervals are corrosive.19. The method of claim 16, wherein the problematic intervals are of ahigh-pressure differential.
 20. The method of claim 16, wherein thedeployment line remains above the problematic intervals in the wellduring logging operations.